Pyrimidine phosphorothioates



United States Patent 3,243,437 PYRIMIDINE PHOSPHOROTHIOATES Edward Sherlock, Braclrnell, England, assignor to Imperial Chemical Industries Limited, London, England, a corporation of Great Britain No Drawing. Original application Apr. 11, 1960, Ser. No. 21,133. Divided and this application Feb. 10, 1965, Ser. No. 431,725 Claims priority, application Great Britain, Apr. 23, 1959, 13,940/59 4 Claims. (Cl. 260-251) This is a division of my earlier application Serial No. 21,133, filed April 11, 1960, now US. Patent No. 3,185,699.

This invention relates to new heterocyclic compounds and their salts, and to pesticidal compositions containing them. The invention is a modification of the invention described in prior US. application Serial No. 764,498, filed October 1, 1958, now abandoned.

Serial No. 764,498, filed October 1, 1958 described and claims s-triazine derivatives of the formula:

in which R and R are methyl or ethyl radicals; R R R and R which can be the same or different, are each a hydrogen atom or a methyl, ethyl, propyl or butyl radical, or R and R or R and R together with their adjacent nitrogen atom constitute a piperidino ring; and X is an atom of oxygen or sulphur, and acid addition salts thereof. These compounds possess aphicidal properties.

It has now been found that many heterocyclic compounds and their salts having structures similar to those of the compounds described above have pesticidal properties; in particular against aphids and phytophagous mites, for example red spider mites.

Accordingly, the present invention provides new heterocyclic compounds of the formula:

in which R and R" are alkyl radicals having up to four carbon atoms; X is an atom of oxygen or sulphur; and R is a substituted or unsubstituted pyrimidine ring attached to the carbon atom designated by an asterisk through a carbon atom of said ring, and salts of said compounds.

It has been found that, in general, compounds of the invention in which group X is oxygen have higher activity than the analogous compounds in which X is sulphur.

The heterocyclic ring of the compounds of the invention can contain one or more substituents, for example, alkyl, cycloalkyl, aryl or aralkyl radicals, or amino, hydroxy, or carboxylic ester groups; and the substituents can be carried by either carbon or nitrogen atoms in the ring. Examples of suitable alkyl radicals include alkyl radicals having l-4 carbon atoms, for instance, methyl, ethyl, and propyl radicals. Examples of suitable cycloalkyl, aryl and aralkyl radicals are respectively, cyclohexyl, phenyl and benzyl radicals.

As stated above, the salts of the new heterocyclic compounds defined above are included in the invention. This is true, of course, in respect of any individual compound only in so far as that compound is capable of salt formation; for example, tetrazoles are, in general, not basic compounds and do not form salts. The pre- 3,243,437 Patented Mar. 29, 1966 ferred salts are acid addition salts, which can be salts derived from an organic acid, for example oxalates, or from an inorganic acid, for example hydrochlorides.

The invention also includes a process for the preparation of the compounds of this invention in which a compound of the formula:

YCH R' is reacted with a compound of the formula:

RO RO/ \SM where Y is an atom of chlorine, bromine or iodine, R", R" and X have any of the meanings given to them above, and M is an atom of an alkali metal, for instance sodium or potassium, or an ammonium radical.

The process can be conveniently performed using a solution or dispersion of the reactants in a suitable organic solvent. Suitable solvents are a lower alkanol (for example methanol or ethanol), acetone and dioxane. The temperature required for the reaction naturally depends to a large extent upon the reactivity of the reactants; with some reactants it can take place at room temperature, but generally the reactants need to be heated, for example, to a temperature in the range 40 C. to C., to obtain an adequate rate of reaction. In general, it is convenient to boil under reflux a solution of the reactants in a suitable organic solvent.

The invention also includes pesticidal compositions containing, as active ingredient, a compound of the invention or a salt thereof, in admixture with a suitable diluent or carrier. The pesticidal compositions can, for example, be a liquid composition in which the active ingredient is dissolved or dispersed in a suitable liquid medium or it can be a powder composition.

The compounds of the invention have only low solubility in water, but are, in general, sufiiciently soluble to enable aqueous solutions of low pesticidal concentrations to be prepared. However, in order to facilitate the preparation of aqueous solutions, especially where higher pesticidal concentrations are required, it has been found advantageous to dissolve the compound initially in a small quantity of methanol, tetrahydrofurfuryl alcohol, diacetone alcohol or B-ethoxy ethanol, and to dilute the resulting organic solution with sufficient water to obtain the desired aqueous solution.

Where the pesticidal composition of the invention is a powder composition, the active ingredient can 'be in admixture with an inert pulverulent solid, for example fullers earth, talc, kaolin, kieselguhr or bentonite. If desired, the pesticidal compositions, whether liquid or solid, can contain a suitable wetting or dispersing agent, or other suitable auxiliary agent known in the art as being useful in pesticidal compositions.

The invention also includes a method of combating aphids and phytophagous mites, in which the aphids, mites or plants susceptible to attack by said aphids or mites are treated with a compound or a pesticidal composition of this invention.

The invention is illustrated by the following examples.

Example 1 This example describes the preparation of 4-diethoxyphosphinylthiomethyl imidazole. This compound does not contain a pyrimidine ring in accordance with the invention but the example illustrates the method employed in making the compounds of the invention.

4-chlorornethylimidazole hydrochloride (9 g.) was slu-rried with absolute ethanol (100 cc.) and anhydrous sodium carbonate (3 g.) added to the slurry. The slurry was allowed to stand for 30 minutes, being shaken occasionally, filtered, and the solid thus removed washed with a little ethanol and the washings added to the filtrate which was a solution of 4-chloromethylimidazole.

Sodium :0 diethyl phosphorothiolate (11.3 g.) was 4 time the number of dead aphids were counted and the LD 50 value calculated.

With I. telarius the method of testing was as follows: Small French bean plants in 3" pots were infested added to the filtrate with shaking, the mixture thus obwith adult female mites, and 24 hours later were sprayed tained allowed to stand at room temperature for 2 hours on a turntable with one of the aqueous solutions. In and then filtered to remove the sodium chloride which each instance the spray was applied until excess of the had precipitated. The solvent was removed from the solution ran off the plant. The plants were then stored filtrate by evaporation under reduced pressure leaving i a h t d greenhouse f 3 days, and at the end of 4-diethoxyphosphinylthiomethyl imidazole as a light th t i d th number of dead ite w o nted brown oily residue. This residue was purified by disand the LD 50 value calculated. Solving it in ether, Washing three times With a Small The results obtained from the tests described above VOlllIne Of Water, drying OVfir anhydrous Sodium Sulphate are set out in Table H which gives the parathion equivaand removing the solvent by distillation under reduced l f h compounds d pressure.

The compounds of this invention have been prepared TABLE H by methods analogous to that described in Example 1 above, and are set out below as Examples 2-4. Compound of Parathlon eqmvalent Table I below (which contains Examples 2-4) shows EXamP1eN0- M pm T. telarms the solvent and t1me of reaction used in preparing the various compounds. The products of Examples 2-4 were A 3 6 0 0 7 prepared by heating the reactants at the reflux tempera- 4:11:11: 513 0:4 ture of the solvent. Table I also defines the halogen atom of the heterocyclic methyl halide and the alkali meta-l of the salt of the O:O'-dialkyl-phosphorothiolic I clalm: or phosphorodithioic acid used as reactants in the prepa- A command Selected from the group conslstmg of ration of the various compounds. The column on the compounds havmg the formula right-hand side of the table gives the melting point (or, R0 X where the compound is a liquid, the boiling point) of the various heterocyclic compounds; and where the compounds are solids, the solvent from which they have been RHO crystallized. in which R and R are alkyl having up to four carbon TABLE I Example Reaction Alkali Solvent of No. Compound Time Solvent Halide metal Properties of Compound Crystal- (hours) lization 2 i CH 5 Methanol." Ohloride Sodium"..- Uudistillable oil onao i N 3 SCHz- 3 H CH 1% Ethanol "do do Melting point 90 C Ethanol.

(C2H5O)2P N SCH 4 S 1 do do "do Melting point 122-3" 0.. Do.

H CH3 2 s )2 I N SCH,

Compounds described in the examples have been tested atoms, X is an atom selected from the group consisting and found to be active against the aphids Macrosiphum of oxygen and sulfur, and R' is selected from the group pisi and the phytopha-gous mites Tetranychms' telarius. consisting of an unsubstituted pyrimidine ring attached Each of the compounds was tested in the form of a to the carbon atom designated by an asterisk through number of aqueous solutions covering arange of concena carbon atom of said ring and a pyrimidine ring attrations, and each containing 0.5% by Weight of a wettached to said carbon atom designated by an asterisk ting agent. Similar aqueous solutions of various concenthrough a carbon atom of said ring and substituted by trations of the commercialp'esticide parathion were used a member of the group consisting of alkyl having 1-4 asastand'ard for comparison. carbon atoms, cyclohexyl, phenyl, benzyl, amino and The method of testing against M. pisi was as follows: hydroxyl and pesticidal acid addition salts of said com- Adult, apterous, viviparous females were'sprayed under pound, a Potter Tower apparatus with 2 cc. of each of the aqueous 2. The compound having the formula solutions of the test chemical and of parathion, three S replicates of 30-40 aphids each being used at each con- CH: centration. After being sprayed, the aphids were trans- (OzH50): N ferred to 2-02. jars containing clean broad bean leaves, SoHzwhich were then stored under conditions of constant tem- N perature and humidity for 24 hours, at the end of which 4. The compound having the formula UNITED STATES PATENTS 2,754,244 7/1956 Gysin et a1 2603 10 XR 5 2,922,739 1/1960 Snyder 260268 XR 3,131,186 4/1964 Magee et a1. 260-249.5

WALTER A. MODANOE, Primary Examiner.

10 JOHN D. RANDOLPH, Examiner.

J. M. FORD, Assistant Examiner. 

1. A COMPOUND SELECTED FROM THE GROUP CONSISTING OF COMPOUNDS HAVING THE FORMULA 